Vintage string party lights add the right kind of ambient light for a relaxed vibe to any backyard. These are well built outdoor rated party lights, great for a backyard wedding, BBQ, or just hanging out fireside. Who needs an occasion?
DIY - Glow in the dark pots with mums for fall/Halloween. Buy a flower pot that you really like and use Rustoleum's Glow-in-the-dark paint to paint the pot. During the day, the paint will absorb the sunlight and at night the pots will glow.
Would this fence idea work for an herb garden? In case you have a dull wooden fence at your backyard you can easily spice up it. You can make a colorful vertical garden of it. Tools and materials - Terra-cot
Elf house on a tree! That would be cute in the garden, especially in the tree over grown with ivy. How about some battery tea lights in the windows during outdoor parties. I hear the fairies/elves whispering "home school project" in my ear.